Introduction to Oracle Datatypes

Each column value and constant in a SQL statement has a data type, which is associated with a specific storage format, constraints, and a valid range of values. When you create a table, you must specify a datatype for each of its columns.

Oracle provides the following categories of built-in datatypes:

• Overview of Character Datatypes
• Overview of Numeric Datatypes
• Overview of DATE Datatype
• Overview of LOB Datatypes
• Overview of RAW and LONG RAW Datatypes
• Overview of ROWID and UROWID Datatypes

The following sections that describe each of the built-in datatypes in more detail.

Overview of Character Datatypes

The character datatypes store character (alphanumeric) data in strings, with byte values corresponding to the character encoding scheme, generally called a character set or code page.

The database's character set is established when you create the database. Examples of character sets are 7-bit ASCII (American Standard Code for Information Interchange), EBCDIC (Extended Binary Coded Decimal Interchange Code), Code Page 500, Japan Extended UNIX, and Unicode UTF-8. Oracle supports both single-byte and multibyte encoding schemes.

This section includes the following topics:

·         CHAR Datatype

·         VARCHAR2 and VARCHAR Datatypes

·         Length Semantics for Character Datatypes

·         NCHAR and NVARCHAR2 Datatypes

·         Use of Unicode Data in Oracle Database

·         LOB Character Datatypes

·         LONG Datatype